Tubular composite materials are used for lining pipes and passages which, for the most part, have a circular cross-section, in particular for the repair of damaged pipelines or canalizations. According to the prior art, composite materials of this type consist of textile sheet structures which are impregnated with reactive resins, for example with styrene-containing polyester casting resins or epoxy casting resins, and of a gas- and liquid-impermeable plastics film. The plastics film may be made of polyethylene, PVC or melt-calandered polyurethane and is optionally firmly joined to the textile substrate. The prior art is described in GB-PS Nos. 1,039,836; 1,357,355; 1,423,819 and 1,449,455, and in DE-OS No. 2,362,784 and DE-PS No. 2,240,153. When polyurethanes are used as the plastics film, the film is produced by melt calandering.
The composite material which is processed into a tube, for example sewn and sealed on the seam, is introduced into pipes to repair damaged areas, for example it is "floated in" with water and inflated with compressed air (process according to DE-PS No. 2,240,153) or is preferably "inverted" by pressure while being introduced into damaged pipelines (inversion process according to DE-OS No. 2,362,784).
In this way, the textile layer, impregnated with reactive resin, which is initially on the inside is turned outside to lie against the wall of the pipe. Hot water may be passed into the pipe system to harden the reactive resin.
The prior art composite materials consisting of textile substrates and film layers have a number of disadvantages. Thus, composite materials based on films of PVC or polyethylene are relatively rigid and relatively inelastic, and they may contain plasticizers. These disadvantages complicate the adaptation of the material to, for example, damaged or corroded pipelines. Even the already practiced use of polyurethane films which are produced on a melt roller calander has disadvantages. Thus, the polyurethane films produced thereby are relatively rigid and the composite material is difficult to process by the "inversion process" of DE-PS No. 2,362,784. Moreover, the adhesion between the textile layer and the PU film is often inadequate and requires the application of an adhesifying layer which considerably complicates the technique (brush coating processes and melt calandering processes both have to be applied). In the case of polyethylenes, the adhesion between the web and the film layer is too weak and the seam is difficult to seal. In the case of PVC, the styrene resistance is inadequate.